It has been estimated by the World Health Organisation that almost one
half of the world's population has heen infected with the tubercle
bacillus. Some 3.5 million new cases are registered a year and one
third of these patients will die. An active (smear positive) case of
tuberculosis would infect up to 40% of susceptible contacts and 10% of
contacts will develop active disease.

It has been estimated by the World Health Organisation that almost one
half of the world's population has heen infected with the tubercle
bacillus. Some 3.5 million new cases are registered a year and one
third of these patients will die. An active (smear positive) case of
tuberculosis would infect up to 40% of susceptible contacts and 10% of
contacts will develop active disease.